What is the cause of Myopia?

There are many reasons why a child might develop Myopia. Some of these include:

Their parents are short-sighted (myopic) and they 'inherit' Myopia

The way they use their eyes may lead to Myopia

They are born premature and with low birth weight

They have an eye condition that is seen along with Myopia

They may have a condition of growth that causes their eyes to grow bigger than normal

If a child's parents are short-sighted the child is more likely to also be short-sighted

If a child has one parent who is short-sighted there is a one in three chance the child will also be short-sighted. If both parents are short-sighted then there is a one in two chance the child will be short-sighted. The child can be said to have 'inherited' the myopia.

Children who use their eyes lots for close work are more likely to become Myopic

There is some evidence that children who use their eyes more for looking at near objects, than other children, are more likely to become myopic. Children who are already myopic may increase their level of myopia. The reason why this occurs is not well understood.

Premature babies are more likely to become Myopic

Babies that are born earlier than usual and of lower birth weight have a one in two chance of becoming myopic. If they also develop a condition called Retinopathy of Prematurity then they are likely to become very short-sighted.

Some eye conditions can cause Myopia

For normal growth of the eye light needs to enter the eye without being blocked. If a child has a hazy cornea (corneal dystrophy) or lens (cataract) not all the light can enter the eye and the vision will be blurred. This may cause the eye to grow bigger and longer than usual. This leads to myopia. This is known as 'Form Deprivation Myopia'. - http://www.ssc.education.ed.ac.uk/resources/vi&multi/eyeconds/myop.html

Premature babies are often short-sighted, and a glaucoma (excessive intraocular pressure) during childhood causes myopia, as well, due to the long deformation of the eyeball.myopia cannot be trained away.

The eye is moved by six externally attached muscles. They are permanently active - also unvoluntarily, even during sleep - and due to the permanent change between tension and relaxation they are in a well-trained state without any additional training.

To influence myopia, these muscles would have to shorten the prolonged eyeball by a simultaneous lateral outside tension (against the ear and the nose). Not only anatomically speaking this is not possible. Even if the muscles - like in several diseases - are under excessive pressure, such as in Basedow´s disease, where the eyes are strongly displaced forward, the shape of the eyeball and thus also short- or far-sightedness do not change at all. On these grounds, Bates theory that the external eye muscles might exert an influence on myopia is a heresy.

Several defenders of Bates exercises intend to remove myopia by relaxation of the orbicular muscle. However, only accommodation, that is near vision, is controlled by this muscle. A normal-sighted eye is adjusted to far-vision in a relaxed state and will create a sharp image. The short-sighted (prolonged) eye will always see everything behind a short distance from the eyes blurred, simply because the image does not arrive on the retina but in front of it. The fact that the relaxation of the orbicular muscle has no stronger effect on short-sightedness than any other ocular muscle becomes clear by merely looking at the examination method used by ophthalmologists with a suspicion of myopia. Here, drugs are used to completely relax the inner orbicular muscle, because short-sightedness can be reliably detected in this way. If Bates was right, myopia would have to disappear during the ophthalmological examination - for the time the drug-induced muscle relaxation continues.

"Relaxation exercises" and "eye muscle training" cannot influence short-sightedness - this was also definitely found by ophthalmologists who, disregarding all theoretical concerns, tried this exercising method in their patients. Where the promises of the defenders of Bates´ theory are only fraud, they become a criminal deed when short-sighted patients are driving without spectacles because they believe their vision is improved after the "exercises". They should better think of their responsibility for others, when driving or working!

How can myopia be optically corrected?

There are two possibilities:

Spectacles or contact lenses (see figures)

Contact lenses:
Contact lenses float on the cornea. A flatter curvature of the contact lens results in sharper retinal images.